The proliferation and popularity of mobile radio and telephony applications has led to market demand for communication systems with low cost, low power, and small form-factor radio-frequency transceivers. As a result, recent research has focused on providing monolithic transceivers using low-cost complementary metal-oxide semiconductor (CMOS) technology. One aspect of research efforts has focused on providing an RF transceiver within a single integrated circuit (IC). The integration of transceiver circuits is not a trivial problem, as it must take into account the requirements of the transceiver's circuitry and the communication standards governing the transceiver's operation. From the perspective of the transceiver's circuitry, RF transceivers typically include sensitive components susceptible to noise and interference with one another and with external sources. Integrating the transceiver's circuitry into one integrated circuit may exacerbate interference among the various blocks of the transceiver's circuitry. Moreover, communication standards governing RF transceiver operation outline a set of requirements for noise, inter-modulation, blocking performance, output power, and spectral emission of the transceiver.
Unfortunately, no technique for addressing all of the above issues in high-performance RF receivers or transceivers, for example, RF transceivers used in cellular and telephony applications, has been developed. A need therefore exists for techniques of partitioning and integrating RF receivers or transceivers that would provide low-cost, low form-factor RF transceivers for high-performance applications, for example, in cellular handsets.
A further aspect of the invention relates to calibration of signal-processing circuitry. Typical analog signal-processing circuitry uses resistors and capacitors. The variation of resistor and capacitor values as a function of physical and environmental changes causes variations in the characteristics or attributes of the signal-processing circuitry. Changes in the characteristics or attributes of the signal-processing circuitry may cause degraded performance of the circuitry or even of the system that includes the signal-processing circuitry. A need therefore exists for calibration of signal-processing circuitry to avoid undesired or detrimental changes in the circuitry's or system's characteristics.